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In this study, we focus on a static spherically symmetric $f(R)$ black hole spacetime characterized by a linear dark matter-related parameter. Our investigation delves into understanding the influence of different assumed values of this…

General Relativity and Quantum Cosmology · Physics 2023-12-21 Mohsen Fathi , Norman Cruz

We develop the idea that, in quantum gravity where the horizon fluctuates, a black hole should have a discrete mass spectrum with concomitant line emission. Simple arguments fix the spacing of the lines, which should be broad but unblended.…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Jacob D. Bekenstein , V. F. Mukhanov

We examine the behavior of non-commutative Schwarzschild black holes in the context of massive gravity. According to the investigation, corresponding to a minimal mass, the black hole can have two horizons, one horizon, or no horizon at…

General Relativity and Quantum Cosmology · Physics 2024-04-17 Piyali Bhar , Dhruba Jyoti Gogoi , Supakchai Ponglertsakul

During the glorious success of the EHT in providing the first image of a black hole, numerous papers have been published about the effect of different astrophysical environments on black hole geometry. Motivated by the work on how…

General Relativity and Quantum Cosmology · Physics 2023-12-08 Reggie C. Pantig

In this work, we consider two recently introduced novel regular black hole solutions and investigate the circular null geodesics to find the connection between the photon sphere, the horizon and the black hole shadow radii. We also study…

General Relativity and Quantum Cosmology · Physics 2022-11-01 Khadije Jafarzade , Mahdi Kord Zangeneh , Francisco S. N. Lobo

This work mainly focuses to unveil the optical features of a black hole. For this objective, we utilize the metric-affine black hole geometry with the inclusion of dilation, spin, and shear charge. The Lagrangian coefficients $f_1$ and…

General Relativity and Quantum Cosmology · Physics 2023-03-10 Allah Ditta , Xia Tiecheng , Saadia Mumtaz , Farruh Atamurotov , G. Mustafa , Ahmadjon Abdujabbarov

The spherically symmetric deformation of the Schwarzschild solution owing to the quantum corrections to gravity is known as Kazakov-Solodukhin black-hole metric. Neglecting non-spherical deformations of the background the problem was solved…

General Relativity and Quantum Cosmology · Physics 2020-03-20 R. A. Konoplya

This study investigates the effects of higher dimensions on the observable properties of Schwarzschild-Tangherlini black holes, focusing on the photonsphere, shadow radius, deflection angles, and quasinormal modes (QNMs). By extending…

General Relativity and Quantum Cosmology · Physics 2025-06-27 Nikko John Leo S. Lobos , Anele M. Ncube , Reggie C. Pantig , Alan S. Cornell

Several works over the past years have discussed the possibility of testing fundamental physics using Very Long Baseline Interferometry horizon-scale black hole (BH) images, such as the Event Horizon Telescope (EHT) images of M87$^*$ and…

Astrophysics of Galaxies · Physics 2022-05-31 Sunny Vagnozzi , Luca Visinelli

Following up on a recent analysis by Psaltis et al. [Phys. Rev. Lett. 125, 141104 (2020)], we show that the observed shadow size of M87$^*$ can be used to unambiguously and robustly constrain the black hole geometry in the vicinity of the…

General Relativity and Quantum Cosmology · Physics 2021-10-13 Sebastian H. Völkel , Enrico Barausse , Nicola Franchini , Avery E. Broderick

Detailed observations of phenomena involving black holes, be it via gravitational waves or more traditional electromagnetic means, can probe the strong field regime of the gravitational interaction. The prediction of features in such…

General Relativity and Quantum Cosmology · Physics 2020-02-19 Andrew Sullivan , Nicolás Yunes , Thomas P. Sotiriou

We investigate cosmology-driven modifications to Schwarzschild-like black hole spacetimes and analyze their impact on photon propagation, gravitational lensing, and shadow observation. The gravitational deflection angle is computed using…

General Relativity and Quantum Cosmology · Physics 2025-09-19 Ritesh Pandey , Shubham Kala , Amare Abebe , Hemwati Nandan , G. G. L. Nashed

In this paper, we investigate the properties of black holes within the framework of multi-fractional theories of gravity, focusing on the effects of q-derivatives and weighted derivatives. These modifications, which introduce…

General Relativity and Quantum Cosmology · Physics 2025-06-03 Reggie C. Pantig

In this paper, we study rotating black holes in symmergent gravity, and use deviations from the Kerr black hole to constrain the parameters of the symmergent gravity. Symmergent gravity induces the gravitational constant $G$ and quadratic…

General Relativity and Quantum Cosmology · Physics 2023-03-28 Reggie C. Pantig , Ali Övgün , Durmuş Demir

We investigate the prospect of using black hole spectroscopy to constrain the parameters of Horndeski gravity through observations of gravitational waves from perturbed black holes. We study the gravitational waves emitted during ringdown…

General Relativity and Quantum Cosmology · Physics 2019-06-18 Oliver J. Tattersall , Pedro G. Ferreira

The reflection spectrum produced by a cold medium illuminated by X-ray photons is not isotropic and its shape depends on the emission angle. In the reflection spectrum of an accretion disk of a black hole, the value of the emission angle…

In this work we study whether parametrized spherically symmetric black hole solutions in metric theories of gravity can appear to be isospectral when studying perturbations. From a theory agnostic point of view, the test scalar field wave…

General Relativity and Quantum Cosmology · Physics 2019-09-04 Sebastian H. Völkel , Kostas D. Kokkotas

Conformal invariance can ameliorate or eliminate the singularities residing in the black holes, and may still exist in the strong gravity regimes close to these black holes. In this paper, we try to probe this conformal invariance by…

General Relativity and Quantum Cosmology · Physics 2020-06-09 Rui-Hui Lin , Rui Jiang , Yang Huang , Xiang-Hua Zhai

Black holes hold a tremendous discovery potential. In this paper the extent to which the Event Horizon Telescope and its next generation upgrade can resolve their structure is quantified. Black holes are characterized by a perfectly…

General Relativity and Quantum Cosmology · Physics 2022-11-16 Raúl Carballo-Rubio , Vitor Cardoso , Ziri Younsi

The horizon-scale images of black holes obtained with the Event Horizon Telescope have provided new probes of their metrics and tests of General Relativity. The images are characterized by a bright, near circular ring from the…

High Energy Astrophysical Phenomena · Physics 2022-12-28 Feryal Ozel , Dimitrios Psaltis , Ziri Younsi